Can you write out the math of what how you want the values of the two textures to be blended together? (background + triangle1 + triangle2). Or, do you want to apply both textures to the same triangle?
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FrogblastFeb 2 '10 at 5:14

The triangles are being rendedered into a separate framebuffer connected to a texture. So in this separate framebuffer the background is (0,0,0,0), the trianlge 1 is simply alpha blended, just like the second triangle (no any add, modulate, etc. like these). You can see these images (so the generated textures) in my previous question here: stackoverflow.com/questions/2173363/…
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GeriFeb 2 '10 at 10:29